Field of the Invention
The present disclosure relates to a nitride fluorescent material, a method for producing the nitride fluorescent material, and a light emitting device.
Description of the Related Art
Light emitting devices have been developed that emit white light by incorporating in combination a blue light emitting LED (Light Emitting Diode) as a light emitting element, a fluorescent material emitting green light when excited by the blue light, and a fluorescent material emitting red light when excited by the blue light. For instance, Japanese patent application JP 2008-303331 A describes a light emitting device that emits white light by incorporating in combination a β sialon fluorescent material having a β-type Si3N4 crystalline structure, and emitting green light; a nitride fluorescent material having a composition of CaAlSiN3:Eu and emitting red light (hereinafter also referred to as “CASN fluorescent material”); and a blue LED.
A red light emitting fluorescent material (hereinafter also referred to as “SCASN fluorescent material”) having a composition of (Ca,Sr)AlSiN3:Eu obtained by partially replacing Ca with Sr in a CASN fluorescent material is known. A SCASN fluorescent material is said to have a peak emission wavelength shorter than the peak emission wavelength of a CASN fluorescent material. A CASN fluorescent material can be obtained by, for instance, calcinating a mixture comprising silicon nitride, aluminium nitride, calcium nitride, and europium nitride. A SCASN fluorescent material can also be obtained in the same manner as a CASN fluorescent material (see, for instance, JP 2006-8721 A).